The two sides discussed a range of environmental issues, including active cooperation to tackle the Aras River pollution during the visit of Armenian nature protection minister Aram Harutyunyan to Tehran, Chitchian said.

The rising pollution levels in the border river have been blamed mainly on the discharge of untreated sewage from an Armenia-based copper factory into the river water.

Armenia established a waste water recycling plant beside the Zangezur copper factory earlier to prevent the river's pollution, Chitchian said, adding that but it has not operated continuously.

The two sides agreed to online monitoring of the recycling plant to ensure the process is not halted, he underlined.

The recycling plant was created by Armenian assets and Iran has not paid any money for its establishment, the minister said.

The Araz is a river located in and along the countries of Turkey, Armenia, Azerbaijan, and Iran. Its total length is 1,072 kilometers. Given its length and a basin that covers an area of 102,000 square kilometers, it is one of the largest rivers of the Caucasus.

It joins with the Kura River at the village of Sabirabad and then directly flows into the Caspian Sea.

More than 350 million cubic metres of chemically and biologically polluted water annually are injected into the Kura River (without neutralisation) from the territory of Armenia, and heavy metals, phenols, oil products, radioactive and other harmful substances can be observed in the water samples, Azerbaijani Environment and Natural Resources Ministry announced in 2007.

Armenian Zangezur Copper Molybdenum Combine, which produces some 40,000 tons of copper each year, is one of the main sources of the Araz River pollution.

The recent monitoring of the Azerbaijani Environment and Natural Resources Ministry (first decade of February) indicates that biogenic substances in the Kur and Araz rivers exceed normal levels. The monitoring results revealed that untreated waste water and sewage industry run off from the territory of Georgia and Armenia has made the amount of biogenic substances in the Kur River and its tributaries much higher than normal, the Ministry said.

The level of phenol and copper in the water has exceeded the norm in the Aghstafachay River as well as the Araz River.

Zangezur Copper and Molybdenum Combine is the Armenian government's largest taxpayers. In January-September 2013, the Combine replenished the Armenia's state budget with some $63.8 million.